Soldering apparatus presently available include a soldering apparatus that relies upon a flow soldering method in which a board on which electronic parts have been mounted in advance is dipped in a soldering bath to perform soldering, and a soldering apparatus that relies upon a reflow soldering method in which electronic parts are placed on a soldering cream that has been applied to part mounting positions on the surface of a board and the electronic parts are welded by application of heat.
However, each of these conventional soldering apparatus can be applied only to cases in which identical soldering conditions hold for all parts; they cannot be applied to cases where parts having markedly different thermal capacities or parts having a very small pitch between their leads are mounted on a board. These apparatus require that such parts be soldered individually manually or by robot.
The development of electronics manufacturing techniques has been accompanied by a diversification in the form of the electronic parts used. An increase in specially ordered parts and parts of a type different from the standard type has been accompanied by an increase in soldering locations that are unsuited to blanket soldering by soldering apparatus of the above-mentioned kind, and boards appear which require that all parts be soldered under individual conditions.
Practical application of an automatic soldering apparatus capable of performing soldering on a board automatically under soldering conditions that differ for each part is desired. In such an automatic soldering apparatus, it is required that the positions at which parts are to be soldered, the kinds of parts and the kinds of soldering conditions be instructed for each type of board before the soldering operation. The instructing operation is referred to as "teaching". The data taught includes information relating to part mounting positions on the board, types of parts to be mounted and soldering conditions necessary for automatic soldering.
In order to manually enter soldering conditions for each type of board and for each type of part, however, a great amount of time and labor is required and the automatic soldering apparatus cannot be operated during the teaching operation.
With regard to a printed circuit board on which many parts have been mounted by soldering, it is required that an inspection be performed after the soldering operation in order to determine whether soldering has been carried out appropriately. In order to meet this goal, automatic inspection apparatus that use image processing techniques to automatically inspect the quality of the soldered locations of each part on printed circuit boards having a large number of parts mounted thereon are being put into practical use. These automatic inspection apparatus detect the positions of faulty soldered locations on a printed circuit board as well as the types of faults and print out the results of detection on prescribed recording paper.
FIG. 30 illustrates a specific example of a recording paper 300 outputted by an automatic inspection apparatus. Numeral 301 denotes the outline of a printed circuit board, and number 302 designates the outline of a mounted part. Mounted parts at which faulty soldered locations do not exist are indicated in white on the inner side of the outline 302, whereas mounted parts at which faulty soldered locations do exist are indicated in black on the inner side of the outline 302. Further, the type of soldering defect, such as an excessive or insufficient amount of solder, regarding each faulty soldered location appears at suitable locations on the recording paper 300.
The recording paper 300 is sent to a soldering-defect correction line together with the relevant printed circuit board. While observing the recording paper 300, a worker manually corrects the faulty soldered locations using a soldering iron.
However, correcting a faulty soldered location by a manual operation places a great burden upon the worker. Even if inspection of soldering is automated using an automatic inspection apparatus, human intervention is needed to correct the faulty soldered location. This places a limit upon the improvement that can be made in the overall operating efficiency of the part mounting operation and upon streamlining of the operation.
In order to solve this problem, the development of apparatus for automatically correcting soldering defects has made progress in recent years. This apparatus is capable of correctly faulty soldered locations automatically.
In such apparatus for automatically correcting soldering defects, it is required that the automatic correction apparatus be taught information, which is required to correct faulty soldered locations, before the correcting operation, this information being position information indicating the faulty soldered locations and information relating to correction conditions needed to correct the faulty soldered locations. This operation generally is referred to as "teaching". The correction conditions generally differ for each part. The information relating to the correction conditions includes such information as the soldering-iron approach angles relative to a soldering location, the amount of solder supplied and heating time, etc.
However, entering the above-mentioned correction condition information with regard to all printed circuit boards and all parts that are the object of soldering correction requires a great amount of time and labor, and the apparatus for automatically correcting soldering defects cannot be operated during the teaching operation.